With regard to an electron gun in an electronic microscope, various modifications have been made to obtain a high-resolution and high-luminance observation image. Examples of an electron source using the electron gun include a field emission type electron source, a Schottky type electron source, and the like. The electron sources have characteristics in which the tip end of the emitter used in the electron gun is made to be sharp so as to allow an electric field concentration effect to occur at the tip end, and more electrons are emitted from the tip end.
In recent, it is reported that an electron is emitted from a hafnium carbide nanowire, and the hafnium carbide nanowire functions as an emitter (for example, refer to Non-Patent Document 1). However, it can be seen that electron emission characteristics from the hafnium carbide nanowire in Non-Patent Document 1 are deficient in stability, and there is a demand for an improvement in stability.